212 



them all : we have at least treated of them all in a cur- 

 sory manner. But we have not examined them all 

 under their various aspects. There is one of them, 

 which being considered in a certain point, of view, ma^ 

 perhaps, procure us what we have in vain searched for 

 in the others. 



We may now consider the position of those organs by 

 \vliich plants and animals receive their nourishment. 

 These organs in plants are the roots and leaves : both 

 of them are furnished with pores, by means of which 

 they pump in the nutritious juice. These pores termi- 

 nate at small vessels, which transmit the juice into the 

 inner part ; or, rather, these pores are only the extre- 

 mity of these vessels. 



Animals have organs which are entirely analogous to 

 roots and leaves ; I mean lacteal veins, or vessels which 

 answer the same purpose : these veins open themselves 

 in the intestines, and pump the chyle into them, which 

 they convey into the channel of circulation. An animal 

 is then an organized body, which is nourished by roots 

 placed within him : a plant is an organized body, 

 which receives its nourishment by means of roots placed 

 en its outside. 



Yet an animal which is nourished by pores distri- 

 buted on its outside, renders this character ambiguous. 

 The tape-worm seems such an animal. It forms in the 

 intestines a great number of plaits ; and sometimes en- 

 tirely fills the capacity of this canal. Each of the rings 

 that compose it, and whose length is rarely more than 

 one or two lines, is pierced with a small round aperture, 

 by which one may see the chyle issue, which the worm 

 is full of, and which constitutes its principal nourish- 

 ment : if this aperture is a kind of sucker, by the help 

 of which the insect pumps the chyle that surrounds it, 

 this method of nourishing itself varies but little from 

 that of plants. 



But, without seeking very far for examples of animals 



